1. Field
This invention relates generally to suction control valves. It is specifically directed to such valves in medical applications, and provides a system in which an improved such valve may be used in association with suction probes of various types, including catheter assemblies.
2. State of the Art
Suction delivery systems, particularly in a hospital or laboratory environment, typically require control valves with special capabilities. As an example, systems for endotracheal suctioning typically include a manifold enabling introduction of ventilating gases and intermittent exhalation of patient breath simultaneously with insertion and operation of a tracheal suctioning catheter. The manifold structure typically includes multiple ports, one of which is interfaced to a patient through a patient connection device of some type. The suction catheter is often included within an assembly which is connectable to a second port of the manifold. The catheter assembly conventionally includes a collapsible plastic envelope - entirely surrounding the catheter. A practitioner manually externally collapses the envelope onto the external surface of the catheter, and advances the catheter through the manifold into the throat of a patient, retracting the catheter in a similar fashion following the aspiration procedure. A suction control valve is carried by the other end of the catheter, and connects the lumen of the catheter to a vacuum source.
A suction catheter may be viewed as a special case of suction probes generally. For example, suction is also used to remove mucus and other fluids from the nasal passages and/or oral cavities of patients. A suction control valve is often used in connection with wands or other probes specifically designed for such special applications. The control valve is generally structured to have a normally closed condition which can be overcome with finger pressure applied to an actuator, such as a plunger, lever or knob. In some instances, the valve may be capable of regulating the level of suction applied, but more importantly, the valve should have a reliable biasing system to isolate the vacuum source except when a vacuum is intentionally and deliberately applied.
Various expedients have been proposed for controlling and/or regulating the application of suction through a suction catheter. U. S. Pat. No. 4,569,344 illustrates a typical arrangement in which a suction catheter is connected to a vacuum source through an aspirating vacuum control valve. The valve provides a flow channel which is axial with respect to the catheter lumen. The channel comprises oppositely directed conduits, one of which is fixed to the catheter and the other of which is connectable to a vacuum supply tube. The channel is normally sealed against flow by a resilient seal member. A valve actuator member may be pressed down, thereby moving a plunger against the normal bias of the seal member. The seal is thereby distorted, opening the catheter lumen to the vacuum source. The actuator may be turned to lock the stem into its closed position. U.S. Pat. No. 5,064,168 discloses a control valve of much simpler construction. Unlike the '344 valve, the flow path through the '168 valve is at right angles; the valve is structured to attach to a standard medical luer taper and the bias mechanism of the valve is placed out of the fluid flow path.
While previously available catheter assemblies and their associated suction control valves have been useful, they all have certain shortcomings. A permanent connection to the catheter assembly restricts use of the valve to a single purpose. Conventional orientation of the valve with respect to the lumen of the catheter, or other probe, requires actuation at right angles to the lumen. This mode of actuation is ergonomically disadvantageous for handed-handed operation. Catheter assemblies typically include relatively expensive fixtures at opposite ends. The entire assembly must be discarded with the catheter, even though a procedure which requires periodic catheter replacement may not inherently require replacement of the end fixtures.
There remains a need for a medical suction system of improved versatility and economy. There is a particular need for an integrated modular system which permits the selective discard of individual components while retaining more expensive components for continued use during a procedure or, in appropriate circumstances, multiple use. The avoidance of patient discomfort and enhanced convenience of use are also desirable objectives in the field of this invention.